Method, device and system for assigning ack channels to users

ABSTRACT

A method for assigning acknowledgement (ACK) channels to a user is used to feed back ACKs of a plurality of downlink sub-frames in one uplink sub-frame. According to the method, reserved ACK channels are divided into blocks according to the number of downlink sub-frames; each downlink sub-frame corresponds to one block; each block is divided into several sub-blocks; control channel element (CCE) sets within the same sub-frame are respectively mapped to different sub-blocks; and the ACK channels are assigned to the downlink sub-frames according to a sequence of increasing a mapping label d first and then increasing a sub-block label m. Thus, more unused ACK channels can be released to form resource blocks (RBs) for transmission on other channels, for example, for PUSCH transmission. Other methods for assigning ACK channels to a user, a device for assigning ACK channels to a user, and a communication system are further provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/543,005, filed on Aug. 18, 2009, which is a continuation ofInternational Application No. PCT/CN2009/071124, filed on Apr. 1, 2009.The International Application claims the priority to Chinese patentapplication No. 200810067047.4, filed on Apr. 29, 2008, and Chinesepatent application No. 200810108466.8, filed on Jun. 2, 2008. Theafore-mentioned patent applications are hereby incorporated by referencein their entireties.

FIELD OF THE INVENTION

The present invention relates to the field of mobile communication, andmore particularly to a technique for assigning acknowledgement (ACK)channels to a user.

BACKGROUND OF THE INVENTION

In an existing 3^(rd) Generation Partnership Project (3GPP) EvolvedUniversal Terrestrial Radio Access (E-UTRA) system, network sideequipment, for example, a base station (BS), delivers downlink controlsignaling before sending downlink data, so as to instruct a user toreceive the downlink data from corresponding resources. Upon receivingthe downlink data, the user feeds back an acknowledgement (ACK) if thedownlink data is correctly received; otherwise, the user feeds back anegative-acknowledgement (NAK). User equipment (UE) that receives thedownlink data may support two modes, namely, a frequency division duplex(FDD) mode and a time division duplex (TDD) mode.

For the UE that supports the TDD mode, channels for carrying the ACK/NAKfeedback information of the user are ACK channels. The ACK channels areassigned by the network side according to a rule predefined by thesystem. The user has already acquired the predefined rule, and detectsthe assigned ACK channels according to the predefined rule, and thencarries the feedback information on the channels and sends the feedbackinformation to the network side equipment.

In the prior art, a frame structure in the TDD mode is generally asshown in FIG. 1. Each radio frame is 10 ms long, and consists of twohalf-frames that are respectively 5 ms long. Each half-frame consists ofeight slots that are respectively 0.5 ms long and three special fields,DwPTS, GP, and UpPTS. Every two slots constitute one sub-frame, and thethree special fields, DwPTS, GP, and UpPTS, constitute a specialsub-frame. Each sub-frame is 1 ms long. Among the sub-frames, thesub-frames 0 and 5 are downlink sub-frames, the sub-frame 2 is an uplinksub-frame, DwPTS in the special sub-frame may transmit downlink data ormay not transmit data, and the remaining sub-frames may be flexiblyassigned as uplink sub-frames or downlink sub-frames.

Currently, seven downlink-to-uplink configurations are defined in the3GPP E-UTRA system, including three configurations for the 5 msdownlink-to-uplink switch-point periodicity, namely, 1:3, 2:2, and 3:1;and four configurations for the 10 ms downlink-to-uplink switch-pointperiodicity, namely, 6:3, 7:2, 8:1, and 3:5. Except the two ratios of1:3 and 3:5, all the other ratios are required to feed back ACKs or NAKsof N (N>1, N is an integer) downlink sub-frames in one uplink sub-frame.As known to those skilled in the art that, N>1 is a unique condition forthe TDD mode, and the ACK/NAK assignment problem for a plurality ofdownlink sub-frames under this condition needs to be solved. Meanwhile,the solutions proposed under the condition of N>1 should also cater tothe condition of N=1, so as to reduce the complexity of the system inthe TDD mode.

As the time-frequency resources occupied by a physical downlink controlchannel (PDCCH) are measured by taking control channel elements (CCEs)as the unit, an ACK channel for ACK or NAK uplink feedback is implicitlymapped by a CCE with the smallest label occupied by the PDCCH. Acommonly used implicit mapping mode is one-to-one mapping of CCE labelsto ACK labels.

In the 3GPP system, the number of symbols n occupied by the PDCCH asindicated by a physical control format indicator channel (PCFICH) ineach downlink sub-frame may be 1, 2, or 3; and as for the specialsub-frame, n may be 1 or 2. The value of n for each sub-framedynamically varies. In a downlink sub-frame, under the given systemparameters such as system bandwidth and pilot antenna configurationremain constant, the greater the number n of symbols occupied by thePDCCH is, the more CCEs will exist in the downlink sub-frame. When n is1, 2, and 3, the number of CCEs in the downlink sub-frame is representedby N_(CCE,1)N_(CCE,2), and N_(CCE,3), and N_(CCE,1)<N_(CCE,2)<N_(CCE,3).

According to the prior art, when it requires feeding back ACKs/NAKs of Ndownlink sub-frames in one uplink sub-frame, the network side assignsACK channels to the user according to the following rule.

(1) Considering that n may be provided with different values, thenetwork side reserves f(N_(CCE,3)) ACK channels for each downlinksub-frame (including the special sub-frame) according to the maximum CCEnumber, and adopts a manner of one-to-one mapping of CCEs to ACKs, inwhich f(N_(CCE,3))=N_(CCE,3). The function f represents a mapping rulebetween CCE labels and ACK channel labels. For N sub-frames, a totalnumber of N×N_(CCE,3) ACK channels are reserved.

(2) The N×N_(CCE,3) ACK channels are divided into N consecutiveportions, and each downlink sub-frame is mapped to one portion accordingto the original sequence, and each portion has a size of N_(CCE,3). Forexample, when it requires feeding back ACKs/NAKs of two downlinksub-frames in one uplink sub-frame, a corresponding mapping mode is asshown in FIG. 2, in which the maximum PCFICH values of downlinksub-frames 0 and 1 are both 3.

Difficulties can be experienced when implementing the foregoing rule toassign ACK channels, as unused ACK channels cannot be effectivelyreleased to form resource blocks (RBs) for the physical uplink sharedchannel (PUSCH) transmission.

SUMMARY OF THE INVENTION

Various embodiments of the present invention provide a technique forassigning ACK channels to a user, so that the required ACK channelresources are saved.

A method for assigning ACK channels to a user provided in one embodimentof the present invention is used to feed back ACKs of N downlinksub-frames in one uplink sub-frame. The method includes the followingsteps.

Firstly, reserved ACK channels are divided into N blocks; each downlinksub-frame is assigned with a mapping label d, in which each mappinglabel corresponds to one block; and each block is divided into aplurality of sub-blocks, and each sub-block is assigned with a sub-blocklabel m.

Then, the ACK channels are assigned to the downlink sub-frames accordingto a sequence of increasing the mapping label d first and thenincreasing the sub-block label m. Here, N is a positive integer.

A method for assigning ACK channels to a user provided in one embodimentof the present invention is used to feed back ACKs of N downlinksub-frames in one uplink sub-frame. The method includes the followingsteps.

ACK channels are assigned to the downlink sub-frames using the followingequation according to a sequence of increasing a mapping label d firstand then increasing a sub-block label m:

n _(PUCCH) ⁽¹⁾=(N−d−1)×INTEGER(N _(CCE,m) /K)+d×INTEGER(N _(CCE,m+1)/K)+└n _(CCE) /K┘.

In the above equation, n_(CCE) is a label of a CCE in a sub-frame,n_(PUCCH) ⁽¹⁾ is a label of an ACK channel assigned to a CCE with alabel of n_(CCE) in a sub-frame with a mapping label d, N_(CCE,m)represents the number of CCEs in the downlink sub-frame when n is equalto m, and K and N are positive integers.

A method for assigning ACK channels to a user provided in one embodimentof the present invention is used to feed back ACKs of N downlinksub-frames in one uplink sub-frame. In this method, reserved ACKchannels are divided into N blocks; each downlink sub-frame correspondsto one block according to a preset sequence; each block is divided intoa plurality of sub-blocks; and the ACK channels are assigned to thedownlink sub-frames in a mode of mapping different CCE sets within thesame sub-frame to different sub-blocks respectively.

A method for assigning ACK channels to a user provided in one embodimentof the present invention is used to feed back ACKs of a plurality ofdownlink sub-frames in one uplink sub-frame. According to the method,among reserved N×N_(CCE,max{Mi}) or

$\sum\limits_{i = 0}^{N - 1}N_{{CCE},{Mi}}$

ACK channels, the ACK channels are consecutively mapped to each downlinksub-frame.

A method for assigning ACK channels to a user provided in one embodimentof the present invention is used to feed back ACKs of a plurality ofdownlink sub-frames in one uplink sub-frame. According to the method,reserved ACK channels are divided into N blocks; each downlink sub-frameis assigned with a mapping label d according to a preset rule, in whicheach mapping label corresponds to one block; each block is divided intoa plurality of sub-blocks; and the ACK channels are assigned to thedownlink sub-frames in a mode of mapping K consecutive CCEs to one ACKchannel according to a sequence of increasing the mapping label d firstand then increasing a sub-block label m. Here, K is an integer equal toor greater than 1.

A method for assigning ACK channels to a user provided in one embodimentof the present invention is used to feed back ACKs of a plurality ofdownlink sub-frames in one uplink sub-frame. According to the method,reserved ACK channels are divided into N blocks; the plurality ofdownlink sub-frames is assigned with the same mapping label d accordingto a preset rule, in which each mapping label corresponds to one block;each block is divided into a plurality of sub-blocks; and the ACKchannels are assigned to the downlink sub-frames according to a sequenceof increasing the mapping label d as first and then increasing asub-block label m.

A device for assigning ACK channels to a user provided in one embodimentof the present invention includes a reservation unit and an assignmentunit. The reservation unit is configured to reserve ACK channels for Ndownlink sub-frames. The assignment unit is configured to divide thereserved ACK channels into N blocks; assign each downlink sub-frame witha mapping label d according to a preset rule, in which each mappinglabel corresponds to one block; divide each block into a plurality ofsub-blocks; and assign the ACK channels to the downlink sub-framesaccording to a sequence of increasing the mapping label d first and thenincreasing a sub-block label m.

A device for assigning ACK channels to a user provided in one embodimentof the present invention includes a reservation unit and an assignmentunit. The reservation unit is configured to reserve N×N_(CCE,max{Mi}) or

$\sum\limits_{i = 0}^{N - 1}N_{{CCE},{Mi}}$

ACK channels for N downlink sub-frames. The assignment unit isconfigured to assign the ACK channels to the downlink sub-frames in amode of consecutively mapping ACK channels to each sub-frame among thereserved ACK channels.

A communication system provided in one embodiment of the presentinvention includes UE and any of the above devices. The device islocated at a network side and configured to assign ACK channels to theUE. The UE feeds back ACK information of N downlink sub-frames to thenetwork side on the assigned ACK channels.

A communication system provided in one embodiment of the presentinvention includes any of the above devices.

According to the embodiments of the present invention, the reserved ACKchannels are divided into blocks according to the downlink sub-frames,each block is divided into a plurality of sub-blocks, and the CCE setswithin the same sub-frame are respectively mapped to differentsub-blocks, so as to release unused ACK channel resources as wholeblocks to form more RBs for the transmission on other channels, forexample, PUSCH transmission. Alternatively, ACK channels areconsecutively mapped to each sub-frame among the reserved ACK channels,so as to release unused ACK channel resources as whole blocks, therebysaving the ACK channel resources. Alternatively, a plurality ofconsecutive CCEs is mapped to one ACK channel, or a plurality ofdownlink sub-frames is assigned with the same mapping label, so as toreduce the overhead of resource reservation, thereby saving the ACKchannel resources.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in detail below with reference to theaccompanying drawings, in which:

FIG. 1 is a schematic view of a frame structure in a TDD mode in theprior art;

FIG. 2 is a schematic view of a mapping mode in the prior art;

FIG. 3 is a schematic flow chart of a method according to an embodimentof the present invention;

FIG. 4 is a schematic view of a mapping mode according to an embodimentof the present invention;

FIG. 5 is a schematic view of another mapping mode according to anembodiment of the present invention;

FIG. 6 is a schematic view of still another mapping mode according to anembodiment of the present invention;

FIG. 7 is a schematic structural view of a device according to anembodiment of the present invention; and

FIG. 8 is a schematic structural view of a system according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

During the process of implementing the embodiments of the presentinvention, the inventor(s) found that, when the ACK channels areassigned to a user according to the prior art, the unused ACK channelscannot be effectively released to form RBs for the PUSCH transmission.For example, when ACKs/NAKs of two downlink sub-frames are fed back inone uplink sub-frame, and an actual value of n indicated by PCFICH ofthe sub-frame 0 is 1, labels of the ACK channels that may be actuallyused among ACK channels with labels of 0˜N_(CCE,3)−1 that are mapped tothe sub-frame 0 may be merely in the range of 0˜N_(CCE,1)−1, and theother ACK channels with labels of N_(CCE,1)˜N_(CCE,3)−1 cannot beoccupied by implicit mapping. As a result, the resources occupied bysuch unused ACK channels cannot be released as whole blocks, that is, itis difficult for the idle resources to form RBs once being released.

In an embodiment of the present invention, as shown in FIG. 3, when itrequires feeding back ACKs/NAKs of N downlink sub-frames in one uplinksub-frame, the network side assigns ACK channels to the user accordingto the following rule.

In Step 101, ACK channels are reserved for each downlink sub-frame.Considering that the value of n for each sub-frame varies dynamically,N_(CCE,max{Mi}) ACK channels are reserved for each sub-frame (includingthe special sub-frame), so that a total number of N×N_(CCE,max{Mi})channels are reserved. Here, Mi represents a maximum possible value of nfor a downlink sub-frame with a label of i among N downlink sub-frames;i=0, 1, . . . , N−1; Max {Mi} represents a maximum value of Mi; andN_(CCE,max{Mi}) represents the number of CCEs in the downlink sub-framewhen n is equal to Max {Mi}.

For example, in the current 3GPP E-UTRA system, for the specialsub-frame, n has a maximum value of 2, i.e., Mi=2; and for the othersub-frames, n has a maximum value of 3, i.e., Mi=3, so that Max {Mi} is3. The number of ACK channels reserved for each sub-frame is N_(CCE,3).

In Step 102, CCEs of N sub-frames are mapped to the reserved ACKchannels. Specifically, the reserved ACK channels are divided into Nblocks, and each block is divided into max{Mi} sub-blocks. For Ndownlink sub-frames, each sub-frame corresponds to one block in a presetsequence; and CCE sets with labels of {0, 1, . . . , N_(CCE,1)−1},{N_(CCE,1), N_(CCE,1)+1, . . . , N_(CCE,2)−1}, . . . ,{N_(CCE,max{Mi}-1), N_(CCE,max{Mi}-1)+1, . . . , N_(CCE,max{Mi})−1}within the same sub-frame are respectively mapped to differentsub-blocks.

The specific mapping process in Step 102 is illustrated below by takingthe 3GPP E-UTRA system with Max {Mi}=3 as an example. Max {Mi}=3, i.e.,each block is divided into 3 sub-blocks. The CCE sets with labels of {0,1, . . . , N_(CCE,1)−1}, {N_(CCE,1), N_(CCE,1)+1, . . . ,(N_(CCE,2)−1)}, {N_(CCE,2), (N_(CCE,2)+1), . . . , (N_(CCE,3)−1)} withinthe same sub-frame are respectively mapped to different sub-blocks.

In the mapping process, a sub-frame with a label of i (0≦i<N) among theN downlink sub-frames is assigned with a unique mapping label daccording to a preset rule, so as to represent that the sub-frame isplaced at a sub-frame position with a label of d during the mappingprocess, and 0≦d<N. The preset rule may be any one-to-one mapping from aset i={0, 1, . . . , N−1} to a set d={0, 1, . . . , N−1}, for example,d=i; a mapping mode in which the special sub-frame is placed at the lastposition; or a mapping mode in which the sub-frame with the maximumactual value of n is placed at the foremost position, especially, amapping mode in a sequence from the maximum actual value of n to theminimum actual value of n. N_(CCE,m) represents the number of CCEs inthe downlink sub-frame when the PCFICH value is m (0≦m≦max{Mi}−1), andit is defined that N_(CCE,0)=0. Labels of the ACK channels assignedafter the mapping process are represented by n_(PUCCH) ⁽¹⁾, and(N×N_(CCE,3)) ACK channels reserved for the N downlink sub-frames arelabeled as 0˜N*N_(CCE,3)−1 respectively.

In this embodiment, a BS schedules certain UE on the sub-frame with thelabel of d among the N downlink sub-frames, and assigns a label n_(CCE),(0≦n_(CCE)<N_(CCE,3)) to an initial CCE occupied by a PDCCH carrying adownlink scheduling assignment authorization command of the UE.Accordingly, the BS assigns an ACK channel label n_(PUCCH) ⁽¹⁾ to theinitial CCE according to the following process: firstly, according tothe value of n_(CCE), it is determined that a mapped ACK channel belongsto a sub-block with a label of m in the sub-frame with the label of d,in which the determination process includes selecting a value of m frommε{0,1,2} to satisfy Equation (1) N_(CCE,m)≦n_(CCE)≦N_(CCE,m+1)−1; andthen, the value of m obtained in the above step is substituted intoEquation (2) n_(PUCCH) ⁽¹⁾=(N−d−1)×N_(CCE,m)+d×N_(CCE,m+1)+n_(CCE) tocalculate the assigned ACK channel label.

Equation (2) is further illustrated as follows. When the channelcorresponding to n_(CCE) is located in the sub-block with the label of m(0≦m≦max{Mi}−1, for example, m=0, 1 or 2) in the sub-frame with thelabel of d, the first m sub-blocks (i.e., sub-blocks with labels of 0 to(m−1)) of all the N sub-frames are placed ahead thereof, and the first msub-blocks correspond to N×N_(CCE,m) ACK channels; sub-blocks with thelabel of m in the first d sub-frames, i.e. sub-frames with labels of 0to (d−1) among the N sub-frames are also placed ahead thereof, and thesub-blocks with the label of m correspond to d×(N_(CCE,m+1)−N_(CCE,m))ACK channels; and finally, in the sub-block with the label of m of thesub-frame with the label of d, (n_(CCE)−N_(CCE,m)) ACK channelscorresponding to the first (n_(CCE)−N_(CCE,m)) CCEs are also placedahead thereof. Equation (2) is obtained by summing the above three itemstogether.

The UE detects the PDCCH carrying the downlink scheduling assignmentauthorization command of the UE on the sub-frame with the label of d,and gets to know that the label of the initial CCE occupied by the PDCCHis n_(CCE), 0≦n_(CCE)≦N_(CCE,3). The UE gets to know the label n_(PUCCH)⁽¹⁾ of the ACK channel assigned to the initial CCE according to thefollowing process: firstly, according to the value of n_(CCE), it isdetermined that a mapped ACK channel belongs to a sub-block with a labelof m in the sub-frame with the label of d, in which the determinationprocess includes selecting a value of m from mε{0,1,2} to satisfyEquation (1) N_(CCE,m)≦n_(CCE)≦N_(CCE,m+1)−1; and then, the value of mobtained according to Equation (1) is substituted into Equation (2)n_(PUCCH) ⁽¹⁾=(N−d−1)×N_(CCE,m)+d×N_(CCE,m+1)+n_(CCE) to calculate theassigned ACK channel label.

The UE feeds back ACK/NAK information on the ACK channel with the labelof n_(PUCCH) ⁽¹⁾ and the BS detects the fed back ACK/NAK information onthe ACK channel with the label of n_(PUCCH) ⁽¹⁾. If the BS has scheduledthe UE on a plurality of sub-frames among the N sub-frames, the BSassigns a plurality of ACK channel labels to the UE according to theabove mapping mode, and the UE generally adopts the ACK channelcorresponding to the initial CCE of the last detected PDCCH to feed backthe ACK/NAK information.

In the 3GPP E-UTRA system, L ACK channels are code-division multiplexedon one RB, and generally, for a short-cycle prefix sub-frame structure,L=18. User data is scheduled from the RB only when the L ACK channelscode-division multiplexed on the RB are not available. Therefore,adjustment factors may also be introduced in the division of sub-blocksfor “fine adjustment”, i.e., CCE sets with labels of {0, 1, . . . ,N_(CCE,1)−1−Δ}, {N_(CCE,1)−Δ₁, N_(CCE,1)−Δ₁+1, . . . , N_(CCE,2)−1−Δ₂},. . . , {N_(CCE,max{Mi}-1)−Δ_(max{Mi}-1),N_(CCE,max{Mi}-1)−Δ_(max{Mi}-1)+1, . . . , N_(CCE,max{Mi})−1} within thesub-frame are respectively mapped to different sub-blocks. Here, Δ1, Δ2,. . . , Δmax{Mi}−1 are the adjustment factors, and values thereof aredetermined in a sequence of Δmax{Mi}−1, . . . , Δ2, and Δ1, which aregenerally not greater than 3. The introducing of the adjustment factorsaims at forming one or more complete RBs when the number of ACK channelsin different CCE sets of the same sub-frame is close to an integralmultiple of L. In the above descriptions, “each sub-frame corresponds toone block in a preset sequence”, in which the “preset sequence” may bean original sequence of the N downlink sub-frames, a sequence that thespecial sub-frame is placed at the last position, a sequence that thesub-frame with the maximum actual value of n is placed at the foremostposition (if a plurality of sub-frames has the same n value, theplurality of sub-frames may be placed at the foremost positionsaccording to a random sequence), or any other sequence that facilitatesto release more unused ACK channels as whole blocks.

An example in which each sub-frame corresponds to one block according tothe original sequence of the N sub-frames is as shown in FIG. 4.

In the example as shown in FIG. 4, it requires feeding back ACKs/NAKs oftwo downlink sub-frames in one uplink sub-frame, and the Mi for the twodownlink sub-frames is 3. An actual value of n indicated by the PCFICHof the downlink sub-frame 0 is 3, and an actual value of n indicated bythe PCFICH of the downlink sub-frame 1 is 2. Each of the downlinksub-frames 0 and 1 occupies one block sequentially in the originalsequence, i.e., in the sequence that the sub-frame 0 is prior to thesub-frame 1. In the sub-frames 0 and 1, sub-blocks are further occupiedsequentially according to labels. As shown in FIG. 4, the ACK channelresources with labels in the range of{(N_(CCE,3)+N_(CCE,2))˜(2N_(CCE,3)−1)} may be released.

In an example, each sub-frame corresponds to one block in a sequencethat the special sub-frame is placed at the last position. As the n forthe special sub-frame has a maximum value of 2 in the existing 3GPPsystem, more unused ACK channel resources can be released as wholeblocks if the special sub-frame is placed at the last position.

An example in which each sub-frame corresponds to one block in asequence that the sub-frame with the maximum actual value of n is placedat the foremost position is as shown in FIG. 5.

In the example as shown in FIG. 5, it requires feeding back ACKs/NAKs ofdownlink sub-frames 0 and 1 in one uplink sub-frame, and the Mi for thetwo downlink sub-frames is 3. An actual value of n indicated by thePCFICH of the downlink sub-frame 0 is 2, and an actual value of nindicated by the PCFICH of the downlink sub-frame 1 is 3. As the valueof n for the downlink sub-frame 1 is much greater, the downlinksub-frame 1 is placed at the foremost position. As shown in FIG. 5, theACK channel resources with labels in the range of{(N_(CCE,3)+N_(CCE,2))˜(2N_(CCE,3)−1)} may be released. If it requiresfeeding back ACKs/NAKs of more than two downlink sub-frames, each blockmay be preferably assigned to the sub-frames in a sequence from themaximum actual value of n to the minimum actual value of n for thesub-frames, so as to release more unused ACK resources as whole blocks.

In another embodiment, it requires feeding back ACKs/NAKs of N downlinksub-frames in one uplink sub-frame, and the network side assigns ACKchannels to the user according to the following rule.

In Step a, N_(CCE,Mi) ACK channels are reserved for each downlinksub-frame, and a total number of

$\sum\limits_{i = 0}^{N - 1}N_{{CCE},{Mi}}$

ACK channels are reserved.

Different from Step 101, Step a reserves different number of ACKchannels for each downlink sub-frame according to different Mi valuesthereof, rather than reserving N_(CCE,max{Mi}) ACK channels for eachsub-frame, so as to reduce the reserved ACK channel resources, therebysaving the system channel resources.

For example, when the Mi for the special sub-frame is 2 and the Mi forthe other downlink sub-frames is 3, N_(CCE,2) ACK channels are reservedfor the special sub-frame, and N_(CCE,3) channels are reserved for eachof the other downlink sub-frames. As N_(CCE,2) rather than N_(CCE,3) ACKchannels are reserved for the special sub-frame, the reserved ACKchannel resources are reduced.

In Step b, N sub-frames are mapped to the reserved ACK channels.Specifically, the reserved ACK channels are divided into N blocks, andeach block is divided into Mi sub-blocks. Each sub-frame corresponds toone block in a preset sequence. Sub-blocks belonging to different blocksare arranged in an interleaving manner. CCE sets with labels of {0, 1, .. . , N_(CCE,1)−1}, {N_(CCE,1), N_(CCE,1)+1, . . . , (N_(CCE,2)−1)}, . .. , {N_(CCE,Mi-1), N_(CCE,Mi-1)+1, . . . , N_(CCE,Mi)−1} within the samesub-frame are respectively mapped to different sub-blocks. For example,as for the special sub-frame with Mi of 2, the corresponding block isdivided into 2 sub-blocks, and CCE sets with labels of {0, 1, . . . ,N_(CCE,1)−1}, {N_(CCE,1), N_(CCE,1)+1, . . . , (N_(CCE,2)−1)} within thesub-frame are respectively mapped to different sub-blocks. As for thesub-frames with Mi of 3, each block is divided into 3 sub-blocks,sub-blocks belonging to different blocks are arranged in an interleavingmanner, and CCE sets with labels of {0, 1, . . . , N_(CCE,1)−1},{N_(CCE,1), N_(CCE,1)+1, . . . , (N_(CCE,2)−1)}, {N_(CCE,2), (N_(CCE,2),+1), . . . , (N_(CCE,3)−1)} within the same sub-frame are respectivelymapped to different sub-blocks.

For the 3GPP E-UTRA system, if one special sub-frame exists in the Nsub-frames, the special sub-frame is preferably placed at the lastposition, that is, when the mapping label d is assigned to the sub-framewith the label of i, the special sub-frame is always assigned withd=N−1. Accordingly, in Step b, the BS and the UE determine an ACKchannel label n_(PUCCH) ⁽¹⁾ mapped to a CCE with a label of n_(CCE) inthe sub-frame with the label of d according to the following process:firstly, according to the value of n_(CCE), it is determined that amapped ACK channel belongs to a sub-block with a label of m in thesub-frame with the label of d, in which the determination processincludes selecting a value of m from mε{0,1,2} to satisfy Equation (1)N_(CCE,m)≦n_(CCE)≦N_(CCE,m+1)−1; and then, the value of m obtained inthe above step is substituted into Equation (2) n_(PUCCH)⁽¹⁾=(N−d−1)×N_(CCE,m)+d×N_(CCE,m+1)+n_(CCE) to calculate the assignedACK channel label. It should be noted that, as only 2 sub-blocks existfor the special sub-frame, m actually cannot take the value of 2 in theabove determination process of Equation (1), although mε{0,1,2};alternatively, it may also be defined in the determination process ofEquation (1) that mε{0,1} for the special sub-frame.

Adjustment factors may also be introduced in the division of sub-blocksfor “fine adjustment”, i.e., CCE sets with labels of {0, 1, . . . ,N_(CCE,1)−1−Δ₁}, {N_(CCE,1)−Δ₁, N_(CCE,1)−Δ₁+1, . . . , N_(CCE,2)−1−Δ₂},. . . , {N_(CCE,Mi-1)−Δ_(Mi-1), N_(CCE,Mi-1)−Δ_(Mi-1)+1, . . . ,N_(CCE,Mi-1)} within the sub-frame are respectively mapped to differentsub-blocks. Here, Δ1, Δ2, . . . , and ΔMi−1 are the adjustment factors,and values thereof are determined in a sequence of ΔMi−1, . . . , Δ2,and Δ1, which are generally not greater than 3.

The preset sequence may be an original sequence of the N downlinksub-frames, a sequence that the special sub-frame is placed at the lastposition, or a sequence that the sub-frame with the maximum actual valueof n is placed at the foremost position, in which the specific referencemay be made to the above embodiment.

In still another embodiment, it requires feeding back ACKs/NAKs of Ndownlink sub-frames in one uplink sub-frame, and the network sideassigns ACK channels to the user according to the following rule.

In Step a, ACK channels are reserved for each downlink sub-frame.N_(CCE,Mi) or N_(CCE,max{Mi}) ACK channels are reserved for eachsub-frame, i.e., a total number of N×N_(CCE,max{Mi}) or

$\sum\limits_{i = 0}^{N - 1}N_{{CCE},{Mi}}$

channels are reserved.

In Step b, N sub-frames are mapped to the reserved ACK channels.Specifically, the ACK channels are consecutively mapped to eachsub-frame. The N sub-frames may be arranged in a random sequence. Anexample is as shown in FIG. 6. In this example, it requires feeding backACKs/NAKs of two downlink sub-frames in one uplink sub-frame, and the Mifor the two downlink sub-frames is 3. An actual value of n indicated bythe PCFICH of the downlink sub-frame 0 is 2, and an actual value of nindicated by the PCFICH of the downlink sub-frame 1 is 3. After thesub-frame 0 is mapped to the ACK channels, the sub-frame 1 is mapped tothe remaining ACK channels. The consecutive mapping mode can ensure thatno unused ACK channels exist between the ACK channels where eachsub-frame is mapped, thereby enabling more unused ACK channels to bereleased as whole blocks. In the example as shown in FIG. 6, the ACKchannel resources with labels in the range of{(N_(CCE,3)+N_(CCE))˜(2N_(CCE,3)−1)} may be released.

The released ACK channels with the labels in the range of{(N_(CCE,3)+N_(CCE,2))˜(2N_(CCE,3)−1)} may form one or more complete RBsfor the PUSCH transmission.

TABLE 1 Number of CCE n = 1 n = 2 n = 3 1 or 2 4 1 or 2 4 1 or 2 4System transmitting transmitting transmitting transmitting transmittingtransmitting Bandwidth antennas antennas antennas antennas antennasantennas 1.25 MHz   0 0 2 1 4 3  5 MHz 3 3 12 9 20 17 10 MHz 8 8 25 1941 36 20 MHz 17 17 50 39 84 73

As shown in Table 1, under the situation that the system bandwidth is 20MHz and 4 antennas are configured, and n takes values of 1, 2, and 3,N_(CCE,1)=17, N_(CCE,2)=39, and N_(CCE,3)=73. ACK channels with labelsin the range of 112-145 can be released, that is, 34 ACK channels can bereleased. If one RB only can multiplex 18 ACK channels, at least one RBcan be released for the PUSCH transmission.

In the above example, 34 ACK channels can be released. However, as Ltakes the value of 18, the remaining 16 ACK channels that are releasedcannot form a complete RB for the PUSCH transmission. In this case,“fine adjustment” may be performed to map the CCE set with the label of{N_(CCE,2)−Δ₂, N_(CCE,2)−Δ₂+1, . . . , N_(CCE,3)−1} to the lastsub-block, and here, Δ2 takes a value of 2. As such, a total number of36 ACK channels can be released, which can form 2 complete RBs for thePUSCH transmission.

In another example, how to determine the values of Δ1 and Δ2 during“fine adjustment” is illustrated. As shown in Table 1, under thesituation that the system bandwidth is 10 MHz and 1 or 2 antennas areconfigured, and n takes values of 1, 2, and 3, N_(CCE,1)=8,N_(CCE,2)=25, and N_(CCE,3)=41. As 16 (=41−25) and 17 (=25−8) are closeto L (=18), the value of Δ2 is set to 2 first, and then the value of Δ1is set to 3, such that both {N_(CCE,2)−Δ₂, N_(CCE,2)−Δ₂−1, . . . ,N_(CCE,3)−1} and {N_(CCE,1)−Δ₁, N_(CCE,1)−Δ₁+1, . . . , N_(CCE,2)−1−Δ₂}can form complete RBs.

In the above embodiments, there is a one-to-one mapping relationshipbetween CCEs in the sub-frames and ACK channels, and ACK channel setsthat do not overlap each other are reserved for each sub-frame. When itrequires reserving ACK channel resources for the feedbacks of N downlinksub-frames in one uplink sub-frame, a large number of resources may bereserved, especially when N takes a great value. For example, as for the3GPP E-UTRA system, when a downlink-to-uplink ratio is 9:1, and N=9, oneACK channel is reserved for each CCE of each sub-frame, resulting in alarge overhead.

The following methods may be adopted to solve the problem about a largeoverhead of the reserved ACK channel resources.

In Method 1, a plurality of downlink sub-frames is mapped to the sameACK channel set, and the one-to-one mapping of CCE labels to ACK channellabels is still adopted in the sub-frames. That is, a plurality ofdownlink sub-frames is assigned with the same mapping label d in themapping process. For the downlink sub-frames assigned with the samemapping label d, the number of reserved ACK channels is no less than amaximum number of CCEs of any one of the downlink sub-frames. For the3GPP E-UTRA system, this means that if the special sub-frame andordinary downlink sub-frames are assigned with the same mapping label d,N_(CCE,3) ACK channels exist in the corresponding ACK channel setthereof.

The BS may notify the user of the assignment of the mapping label dthrough a high-level signaling, for example, by broadcasting.

The BS and the UE determine an ACK channel label n_(PUCCH) ⁽¹⁾ mapped toa CCE with a label of n_(CCE) in the sub-frame with the label of daccording to the following process: firstly, according to the value ofn_(CCE) it is determined that a mapped ACK channel belongs to asub-block with a label of m in the sub-frame with the label of d, forexample, for the 3GPP E-UTRA system, the determination process includesselecting a value of m from mε{0,1,2} to satisfy Equation (1)N_(CCE,m)≦n_(CCE)≦N_(CCE,m+1)−1; and then, the value of m obtained inthe above step is substituted into Equation (2) n_(PUCCH)⁽¹⁾−(N−d−1)×N_(CCE,m)+d×N_(CCE,m+1)+n_(CCE) to calculate the assignedACK channel label.

In Method 2, ACK channel sets that do not overlap each other arereserved for each downlink sub-frame, but the one-to-one mapping of CCElabels to ACK channel labels is not adopted in the sub-frames, andinstead, a plurality of CCEs may be assigned with the same ACK channel.A commonly used method is to reserve one ACK channel for every K CCEswith consecutive labels. The specific steps are listed as follows.

N×INTEGER(N_(CCE,max{Mi})/K) or

$\sum\limits_{i = 0}^{N - 1}{{INTEGER}\left( {N_{{CCE},{Mi}}/K} \right)}$

channels reserved for N downlink sub-frames are divided into N blocks,and each block contains INTEGER(N_(CCE,max{Mi})/K) orINTEGER(N_(CCE,Mi)/K) or channels. Each downlink sub-frame is assignedwith a mapping label d according to a preset rule, and each mappinglabel corresponds to one block. INTEGER( ) represents a roundingoperation, and may be a round up operation ┌ ┐ or a round down operation└ ┘. It can be seen that, when K is greater than 1, the number of ACKchannels to be reserved is reduced to 1/K of the number of CCEs, so Kmay also be referred to as an ACK resource reduction factor.

When a total number of N×INTEGER(N_(CCE,max{Mi})/K) channels arereserved, i.e., INTEGER(N_(CCE,max{Mi})/K) ACK channels are reserved foreach downlink sub-frame, each block is divided into max{Mi} sub-blocks,and a sub-block with a label of m containsINTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) ACK channels, in which0≦m<max{Mi}. When a total number of

$\sum\limits_{i = 0}^{N - 1}{{INTEGER}\left( {N_{{CCE},{Mi}}/K} \right)}$

channels are reserved, i.e., INTEGER(N_(CCE,Mi)/K) ACK channels arereserved for each downlink sub-frame, each block is divided into Misub-blocks, and a sub-block with a label of m containsINTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) ACK channels, in which0≦m<Mi.

All ACK channels are mapped to the sub-blocks and arranged according toa sequence of increasing the mapping label d first and then increasingthe sub-block label m. For the 3GPP E-UTRA system, one PDCCH may beformed by 1, 2, 4, or 8 CCEs, so K is recommended to take values innonempty subsets of a set {1, 2, 4, 8}, and the specific value of K isnotified by the BS to the user through a high-level signaling.

The BS and the UE determine an ACK channel label n_(PUCCH) ⁽¹⁾ mapped toa CCE with a label of n_(CCE) in the sub-frame with the label of daccording to the following process: firstly, according to the value ofn_(CCE), it is determined that a mapped ACK channel belongs to asub-block with a label of m in the sub-frame with the label of d, forexample, for the 3GPP E-UTRA system, the determination process includesselecting a value of m from mε{0,1,2} to satisfy Equation (3)INTEGER(N_(CCE,m)/K)×K≦n_(CCE)≦INTEGER(N_(CCE,m+1)/K)×K−1; and then, thevalue of m obtained in the above step is substituted into Equation (4)n_(PUCCH)⁽¹⁾=(N−d−1)×INTEGER(N_(CCE,m)/K)+d×INTEGER(N_(CCE,m+1)/K)+└n_(CCE)/K┘ tocalculate the assigned ACK channel label. When K=1, Equations (3) and(4) are simplified to be Equations (1) and (2) respectively.

In Method 2, a mode of mapping a plurality of CCEs to the same ACKchannel is adopted for some sub-frames, and a mode of mapping each CCEto a different ACK channel (i.e., the one-to-one mapping mode of CCElabels to ACK channel labels) is adopted for the other sub-frames.

In Method 2, when INTEGER( ) specifically represents the round downoperation └ ┘, several CCEs remained after K is rounded down in thesub-frames may have no corresponding ACK channels. For example, when└N_(CCE,Mi)/┘ ACK channels are reserved for the sub-frame with the labelof i, if N_(CCE) cannot be exactly divided by K, only CCEs with labelsof 0˜└N_(CCE,Mi)/K┘×K−1 can be mapped to the ACK channels, and the otherCCEs with labels of └N_(CCE,Mi)/K┘×K˜N_(CCE,Mi)−1 cannot be mapped tothe ACK channels according to Equations (3) and (4). Therefore, at theBS side, the CCEs with the labels of └N_(CCE,Mi)/K┘×K˜N_(CCE,Mi)−1 arenot assigned as initial CCEs occupied by a PDCCH carrying a downlinkscheduling assignment authorization command.

In Method 1, certain limitations may be imposed to avoid a collisionbetween ACK channels for a plurality of downlink sub-frames assignedwith the same mapping label d. For example, it is limited that amongCCEs with the same label in the plurality of downlink sub-framesassigned with the same mapping label d, at most one CCE is taken as theinitial CCE occupied by the PDCCH carrying the downlink schedulingassignment authorization command.

In Method 2, certain limitations may also be imposed to avoid acollision between ACK channels in the sub-frames after the mappingprocess. For example, it is limited that among every K CCEs withconsecutive labels, at most one CCE is taken as the initial CCE occupiedby the PDCCH carrying the downlink scheduling assignment authorizationcommand. A simple implementation method is limiting labels of initialCCEs occupied by all PDCCHs carrying the downlink scheduling assignmentauthorization command to be multiples of K.

The effects of the mapping process using Equations (3) and (4) areillustrated below through specific examples. As Equations (1) and (2)are special cases of Equations (3) and (4) when K=1, no example isparticularly provided for Equations (1) and (2) below.

As shown in Table 1, under the situation that the system bandwidth is 20MHz and 2 antennas are configured, and n takes values of 1, 2, and 3,N_(CCE,1)=17, N_(CCE,2)=50, and N_(CCE,3)=84. In this example, thenumber of downlink sub-frames that need to feed back ACKs in one uplinksub-frame is 3, i.e., N=3, and the three sub-frames are all ordinarysub-frames. Therefore, ACK channel labels mapped to CCE labels of eachsub-frame by using Equations (3) and (4) are respectively shown inTables 2, 3, 4, and 5 when K=1, 2, 4, and 8, and INTEGER( ) specificallyrepresents the round up operation ┌ ┐.

TABLE 2 Sub-frame CCE label ACK channel d in sub-frame label d = 0  0 ~16  0 ~ 16 17 ~ 49 51 ~ 83 50 ~ 83 150 ~ 183 d = 1  0 ~ 16 17 ~ 33 17 ~49  84 ~ 116 50 ~ 83 184 ~ 217 d = 2  0 ~ 16 34 ~ 50 17 ~ 49 117 ~ 14950 ~ 83 218 ~ 251 K = 1, N = 3, N_(CCE,1) = 17, N_(CCE,2) = 50,N_(CCE,3) = 84

TABLE 3 Sub-frame CCE label ACK channel d in sub-frame label d = 0  0 ~17 0 ~ 8 18 ~ 49 27 ~ 42 50 ~ 83 75 ~ 91 d = 1  0 ~ 17  9 ~ 17 18 ~ 4943 ~ 58 50 ~ 83  92 ~ 108 d = 2  0 ~ 17 18 ~ 26 18 ~ 49 59 ~ 74 50 ~ 83109 ~ 125 K = 2, N = 3, N_(CCE,1) = 17, N_(CCE,2) = 50, N_(CCE,3) = 84

TABLE 4 Sub-frame CCE label ACK channel d in sub-frame label d = 0  0 ~19 0 ~ 4 20 ~ 51 15 ~ 22 52 ~ 83 39 ~ 46 d = 1  0 ~ 19 5 ~ 9 20 ~ 51 23~ 30 52 ~ 83 47 ~ 54 d = 2  0 ~ 19 10 ~ 14 20 ~ 51 31 ~ 38 52 ~ 83 55 ~62 K = 4, N = 3, N_(CCE,1) = 17, N_(CCE,2) = 50, N_(CCE,3) = 84

TABLE 5 Sub-frame CCE label ACK channel d in sub-frame label d = 0  0 ~23 0 ~ 2 24 ~ 55  9 ~ 12 56 ~ 83 21 ~ 24 d = 1  0 ~ 23 3 ~ 5 24 ~ 55 13~ 16 56 ~ 83 25 ~ 28 d = 2  0 ~ 23 6 ~ 8 24 ~ 55 17 ~ 20 56 ~ 83 29 ~ 32K = 8, N = 3, N_(CCE,1) = 17, N_(CCE,2) = 50, N_(CCE,3) = 84

As seen from the data in Tables 2-5 that, the greater the value of K is,the less ACK channels need to be assigned, so that the overhead on ACKchannel resources is reduced.

Those of ordinary skill in the art should understand that, all or a partof the steps in the above embodiments can be implemented by relevanthardware under an instruction of a program, and the program may bestored in a computer-readable storage medium, such as a read-only memory(ROM) or a random access memory (RAM), a magnetic disk, or an opticaldisk.

It should be understood that, although the steps of the methods aresequentially described in the above descriptions for the convenience ofunderstanding, the sequence of the above steps is not strictly limited.

In an embodiment, a device 701 for assigning ACK channels to a user isas shown in FIG. 7. The device 701 includes a reservation unit 702 andan assignment unit 703. The reservation unit 702 is configured toreserve channels for each downlink sub-frame (including the specialsub-frame), for example, INTEGER(N_(CCE,max{Mi})/K) orINTEGER(N_(CCE,Mi)/K) ACK channels are reserved for each sub-frame,i.e., a total number of N×INTEGER(N_(CCE,max{Mi})/K) or

$\sum\limits_{i = 0}^{N - 1}{{INTEGER}\left( {N_{{CCE},{Mi}}/K} \right)}$

channels are reserved. The assignment unit 703 is configured to assignthe reserved ACK channels to the N downlink sub-frames. Specifically,the assignment unit 703 divides the reserved ACK channels into N blocks;assigns each downlink sub-frame with a mapping label d according to apreset rule, in which each mapping label corresponds to one block;divides each block into a plurality of sub-blocks; and assigns the ACKchannels to each downlink sub-frame according to a sequence ofincreasing the mapping label d first and then increasing a sub-blocklabel m. The preset rule may be a mapping mode in which the specialsub-frame is placed at the last position, or a mapping mode in which thesub-frame with the maximum actual value of n is placed at the foremostposition, especially a mapping mode in a sequence from the maximumactual value of n to the minimum actual value of n for the sub-frames.

During the process of dividing each block into a plurality ofsub-blocks, when INTEGER(N_(CCE,max{Mi})/K) channels are reserved foreach sub-frame, each block is divided into max{Mi} sub-blocks, and asub-block with a label of m containsINTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) channels; and whenINTEGER(N_(CCE,Mi)/K) channels are reserved for each sub-frame, eachblock is divided into Mi sub-blocks, and a sub-block with a label of mcontains INTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) channels.

An assignment mode may be as follows.

The ACK channels are assigned to the downlink sub-frames in a mode ofmapping K consecutive CCEs to one ACK channel; alternatively, the ACKchannels are assigned to the downlink sub-frames in a mode of mapping aplurality of downlink sub-frames to the same ACK channel set.

Alternatively, when each block is divided into max{Mi} sub-blocks, CCEsets with labels of {0, 1, . . . , N_(CCE,1)−1Δ1}, {N_(CCE,1)−Δ1,N_(CCE,1)−Δ1+1, . . . , N_(CCE,2)−1−Δ2}, . . . , {N_(CCE,Mi-1)−ΔMi−1,N_(CCE,Mi-1)−ΔMi−1+1, . . . , N_(CCE,Mi)−1} within the same sub-frameare respectively mapped to different sub-blocks; when each block isdivided into Mi sub-blocks, CCE sets with labels of {0, 1, . . . ,N_(CCE,1)−1−Δ1}, {N_(CCE,1)−Δ1, N_(CCE,1)−Δ1+1, . . . , N_(CCE,2)−1−Δ2},. . . , {N_(CCE,Mi-1)−ΔMi−1, N_(CCE,Mi-1)−ΔMi−1+1, . . . , N_(CCE,Mi)−1}within the same sub-frame are respectively mapped to differentsub-blocks.

In another embodiment, the reservation unit 702 is configured to reserveN_(CCE,max{Mi}) or N_(CCE,Mi) ACK channels for each downlink sub-frame,and the assignment unit 703 is configured to assign the ACK channels tothe downlink sub-frames in a mode of consecutively mapping ACK channelsto each sub-frame among the reserved ACK channels.

In an embodiment, a communication system 801 is provided, as shown inFIG. 8. The communication system 801 includes a device 802 for assigningACK channels to a user and a UE 803. The device 802 further includes areservation unit and an assignment unit, which respectively have thesame functions as the reservation unit 802 and the assignment unit 803.The device 802 is located at a network side, for example, in a BS at thenetwork side. As the UE has already acquired a rule for assigning ACKchannels in advance, the UE directly feeds back ACK information of Ndownlink sub-frames to the network side through the assigned ACKchannels.

It should be understood that, the devices or units in the accompanyingdrawings (or in the embodiments) are merely exemplary and representlogical structures, among which the units shown as separate componentsmay be or may not be physically separated, and the components shown asunits may be or may not be physical units, that is, may be located atone position or distributed to a plurality of network units.

The accompanying drawings and relevant descriptions are merely intendedto illustrate the principle of the present invention, but not to limitthe scope of the present invention. For example, although theembodiments are described based on the 3GPP TDD system, the technicalsolution of the present invention is also applicable to other networksor systems, for example, half-duplex FDD (HD-FDD), as long as itrequires feeding back ACKs/NAKs of a plurality of downlink sub-frames inone uplink sub-frame. Therefore, any modification, equivalent variation,or improvement made without departing from the principle of the presentinvention fall within the scope of the present invention.

What is claimed is:
 1. A method for assigning ACK channels comprising:dividing reserved ACK channels into N blocks; assigning each of aplurality of N downlink sub-frames with a mapping label d, each mappinglabel corresponding to one block; dividing each block into a pluralityof sub-blocks, each sub-block being assigned with a sub-block label maccording to a control channel element (CCE) label n_(CCE) in thedownlink sub-frame; and assigning the ACK channels to the downlinksub-frames according to a sequence of increasing the mapping label dfirst and then increasing the sub-block label m; the N being a positiveinteger.
 2. The method according to claim 1, wherein the CCE labeln_(CCE) in the downlink sub-frame is the initial CCE label occupied by aphysical downlink control channel (PDCCH).
 3. The method according toclaim 1, wherein the sub-block label m is assigned according to the CCElabel n^(CCE) in the downlink sub-frame comprises: selecting a value ofthe m to satisfyINTEGER(N_(CCE,m)/K)×K≦n_(CCE)≦INTEGER(N_(CCE,m+1)/K)×K−1; the N_(CCE,m)representing the number of CCEs in the downlink sub-frame when n isequal to m, the N_(CCE,m+1) representing the number of CCEs in thedownlink sub-frame when n is equal to m+1, the n being the number ofsymbols occupied by the PDCCH, and the K being a positive integer. 4.The method according to claim 3, wherein when a total number ofN×INTEGER(N_(CCE,max{Mi})/K) ACK channels are reserved for N downlinksub-frames, dividing each block into max{Mi} sub-blocks, the sub-blockwith a label of m containing INTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K)ACK channels; the INTEGER( ) representing a round up operation or around down operation, the Mi representing a maximum possible value of nfor a downlink sub-frame with a label of i among N downlink sub-frames,wherein i is equal to each integer of [0, N−1]; the n being the numberof symbols occupied by the PDCCH, the max{Mi} representing a maximumvalue of Mi, and the N_(CCE,max{Mi}) representing the number of CCEs inthe downlink sub-frame when n is equal to max{Mi}.
 5. The methodaccording to claim 3, wherein when a total number of$\sum\limits_{i = 0}^{N - 1}{{INTEGER}\left( {N_{{CCE},{Mi}}/K} \right)}$ACK channels are reserved for N downlink sub-frames, dividing each blockinto Mi sub-blocks, the sub-block with a label of m containingINTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) ACK channels; the INTEGER( )representing a round up operation or a round down operation, the Mirepresenting a maximum possible value of n for a downlink sub-frame witha label of i among N downlink sub-frames, wherein i is equal to eachinteger of [0, N−1], the n being the number of symbols occupied by thePDCCH, and N_(CCE,Mi) represents the number of CCEs in the downlinksub-frame when n is equal to Mi.
 6. The method according to claim 3,further comprising: if K is equal to 1, when a total number ofN×N_(CCE,max{Mi}) channels are reserved for N downlink sub-frames,dividing each block into max{Mi} sub-blocks, CCE sets with labels of {0,1, . . . , N_(CCE,1)−1−Δ₁}, {N_(CCE,1)−Δ₁, N_(CCE,1)−Δ+1, . . . ,N_(CCE,2)−1−Δ₂}, . . . , {N_(CCE,max{Mi}-1)−Δ_(max{Mi})−1,N_(CCE,max{Mi}-1)−Δ_(max{Mi})−1+1, . . . , N_(CCE,max{Mi})−1} within thesub-frame being respectively mapped to different sub-blocks; wherein Δ₁,Δ₂, . . . , Δ_(max{Mi}-1) are adjustment factors.
 7. The methodaccording to claim 6, wherein value of each the Δ₁, Δ₂, . . . ,Δ_(max{Mi}-1) is
 0. 8. The method according to claim 6, furthercomprising: determining the value of each adjustment factors in asequence of Δ_(max{Mi}-1), . . . , Δ₂, Δ₁.
 9. The method according toclaim 3, further comprising: if K is equal to 1, when a total number of$\sum\limits_{i = 0}^{N - 1}N_{{CCE},{Mi}}$ channels are reserved for Ndownlink sub-frames, dividing each block into Mi sub-blocks, CCE setswith labels of {0, 1, . . . , N_(CCE,1)−1−Δ1}, {N_(CCE,1)−Δ1,N_(CCE,1)−Δhd 1+1, N_(CCE,2)−1−Δ₂}, . . . , {N_(CCE,Mi-1)−Δ_(Mi)−1,N_(CCE,Mi-1)−Δ_(Mi-1)+1, . . . , N_(CCE,Mi)−1} within the sub-framebeing respectively mapped to different sub-blocks; wherein Δ₁, Δ₂, . . ., and Δ_(Mi-1) are adjustment factors.
 10. The method according to claim9, wherein value of each the Δ₁, Δ₂, . . . , and Δ_(Mi-1) is
 0. 11. Themethod according to claim 9, further comprising: determining the valueof each adjustment factors in a sequence of Δ_(Mi-1), . . . , Δ₂, Δ₁.12. The method according to claim 1, wherein the assigning of eachdownlink sub-frame with a mapping label d comprises: assigning themapping label according to any one-to-one mapping from a set ofsub-frame label i to a set of mapping label d.
 13. The method accordingto claim 12, wherein the assigning of the mapping label according to anyone-to-one mapping from a set of sub-frame label i to a set of mappinglabel d comprises: assigning a special sub-frame at the last position.14. A method for assigning ACK channels comprising: dividing reservedACK channels into N blocks; assigning each of a plurality of N downlinksub-frames with a mapping label d, each mapping label corresponding toone block; dividing each block into a plurality of sub-blocks, eachsub-block being assigned with a sub-block label m; and assigning the ACKchannels to the downlink sub-frames according to a following equation:n _(PUCCH) ⁽¹⁾=(N−d−1)×INTEGER(N _(CCE,m) /K)+d×INTEGER(N _(CCE,m+1)/K)+└n _(CCE) /K┘; the N being a positive integer, the n_(CCE) being alabel of a control channel element (CCE) in a sub-frame, the n_(PUCCH)⁽¹⁾ being a label of an ACK channel assigned to a CCE with a label ofn_(CCE) in a sub-frame with a mapping label d, the N_(CCE,m)representing the number of CCEs in the downlink sub-frame when n isequal to m, the N_(CCE,m+1) representing the number of CCEs in thedownlink sub-frame when n is equal to m+1, the n being the number ofsymbols occupied by the PDCCH, and the K being a positive integer. 15.The method according to claim 14, wherein the sub-block label m isassigned according to the control channel element (CCE) label n_(CCE) inthe downlink sub-frame.
 16. The method according to claim 15, whereinthe CCE label n_(CCE) in the downlink sub-frame is the initial CCE labeloccupied by a physical downlink control channel, PDCCH.
 17. The methodaccording to claim 15, wherein the sub-block label m is assigned to avalue to satisfyINTEGER(N_(CCE,m)*K)×K≦n_(CCE)≦INTEGER(N_(CCE,m+1)/K)×K−1; N_(CCE,m)representing the number of CCEs in the downlink sub-frame when n isequal to m, N_(CCE,m+1) representing the number of CCEs in the downlinksub-frame when n is equal to m+1, n being the number of symbols occupiedby the PDCCH, and K being a positive integer.
 18. The method accordingto claim 17, wherein when a total number of$\sum\limits_{i = 0}^{N - 1}{{INTEGER}\left( {N_{{CCE},{Mi}}/K} \right)}$ACK channels are reserved for N downlink sub-frames, dividing each blockinto Mi sub-blocks, the sub-block with a label of m containingINTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) ACK channels; the INTEGER( )representing a round up operation or a round down operation, the Mirepresenting a maximum possible value of n for a downlink sub-frame witha label of i among N downlink sub-frames, wherein i is equal to eachinteger of [0, N−1], the n being the number of symbols occupied by thePDCCH, and N_(CCE,Mi) represents the number of CCEs in the downlinksub-frame when n is equal to Mi.
 19. The method according to claim 14,wherein the assigning of each downlink sub-frame with a mapping label dcomprises: assigning the mapping label according to any one-to-onemapping from a set of sub-frame label i to a set of mapping label d. 20.The method according to claim 19, wherein the assigning of the mappinglabel according to any one-to-one mapping from a set of sub-frame labeli to a set of mapping label d comprises: assigning a special sub-frameat the last position.
 21. A non-transitory computer readable mediumcomprising code adapted to be executed to implement a method forassigning ACK channels, the method comprising: dividing reserved ACKchannels into N blocks; assigning each of a plurality of N downlinksub-frames with a mapping label d, each mapping label corresponding toone block; dividing each block into a plurality of sub-blocks, eachsub-block being assigned with a sub-block label m; and assigning the ACKchannels to the downlink sub-frames according to a following equation:n _(PUCCH) ⁽¹⁾=(N−d−1)×INTEGER(N _(CCE,m) /K)+d×INTEGER(N _(CCE,m+1)/K)+└n _(CCE) /K┘; the N being a positive integer, the n_(CCE) being alabel of a control channel element (CCE) in a sub-frame, the n_(PUCCH)⁽¹⁾ being a label of an ACK channel assigned to a CCE with a label ofn_(CCE) in a sub-frame with a mapping label d, the N_(CCE,m)representing the number of CCEs in the downlink sub-frame when n isequal to m, the N_(CCE,m+1) representing the number of CCEs in thedownlink sub-frame when n is equal to m+1, the n being the number ofsymbols occupied by the PDCCH, and the K being a positive integer. 22.The non-transitory readable computer program media according to claim21, wherein the sub-block label m is assigned to a value to satisfyINTEGER(N_(CCE,m)/K)×K≦n_(CCE)≦INTEGER(N_(CCE,m+1)/K)×K−1; N_(CCE,m)representing the number of CCEs in the downlink sub-frame when n isequal to m, N_(CCE,m+1) representing the number of CCEs in the downlinksub-frame when n is equal to m+1, n being the number of symbols occupiedby the PDCCH, and K being a positive integer.
 23. The non-transitoryreadable computer program media according to claim 21, wherein theassigning of each downlink sub-frame with a mapping label d comprises:assigning the mapping label according to any one-to-one mapping from aset of sub-frame label i to a set of mapping label d.
 24. Thenon-transitory readable computer program media according to claim 23,wherein the assigning of the mapping label according to any one-to-onemapping from a set of sub-frame label i to a set of mapping label dcomprises: assigning a special sub-frame at the last position.
 25. Adevice operable to assign one or more ACK channels comprising: aprocessor configured to divide reserved ACK channels into N blocks,assign each of a plurality of N downlink sub-frames with a mapping labeld, in which each mapping label corresponds to one block; divide eachblock into a plurality of sub-blocks, assign each sub-block with asub-block label m; and assign the ACK channels to the downlinksub-frames according to a following equation:n _(PUCCH) ⁽¹⁾=(N−d−1)×INTEGER(N _(CCE,m) /K)+d×INTEGER(N _(CCE,m+1)/K)+└n _(CCE) /K┘; the N being a positive integer, the n_(CCE) being alabel of a control channel element (CCE) in a sub-frame, the n_(PUCCH)⁽¹⁾ being a label of an ACK channel assigned to a CCE with a label ofn_(CCE) in a sub-frame with a mapping label d, the N_(CCE,m)representing the number of CCEs in the downlink sub-frame when n isequal to m, the N_(CCE,m+1) representing the number of CCEs in thedownlink sub-frame when n is equal to m+1, the n being the number ofsymbols occupied by the PDCCH, and the K being a positive integer. 26.The device according to claim 25, wherein: the processor is configuredto assign a value of the sub-block label m to satisfyINTEGER(N_(CCE,m)/K)×K≦n_(CCE)≦INTEGER(N_(CCE,m+1)/K)×K−1; N_(CCE,m)representing the number of CCEs in the downlink sub-frame when n isequal to m, N_(CCE,m+1) representing the number of CCEs in the downlinksub-frame when n is equal to m+1, n being the number of symbols occupiedby the PDCCH, and K being a positive integer.
 27. The device accordingto claim 25, wherein: when N×INTEGER(N_(CCE,max{Mi})/K) channels for Ndownlink sub-frames are reserved, the INTEGER( ) representing a round upoperation or a round down operation, the processor is configured todivide each block into max{Mi} sub-blocks, the sub-block with a label ofm contains INTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) ACK channels; theMi representing a maximum possible value of n for a downlink sub-framewith a label of i among N downlink sub-frames, wherein i is equal toeach integer of [0, N−1], the n being the number of symbols occupied bya physical downlink control channel (PDCCH), max{Mi} representing amaximum value of Mi, N_(CCE,max{Mi}) representing the number of CCEs inthe downlink sub-frame when n is equal to max{Mi}, and K being aninteger equal to or greater than
 1. 28. The device according to claim25, wherein: when$\sum\limits_{i = 0}^{N - 1}{{INTEGER}\left( {N_{{CCE},{Mi}}/K} \right)}$channels for N downlink sub-frames are reserved, the INTEGER( )representing a round up operation or a round down operation, theassignment unit is configured to divide each block into Mi sub-blocks,the sub-block with a label of m containsINTEGER(N_(CCE,m+1)/K)−INTEGER(N_(CCE,m)/K) ACK channels; the Mirepresenting a maximum possible value of n for a downlink sub-frame witha label of i among N downlink sub-frames, wherein i is equal to eachinteger of [0, N−1], the n being the number of symbols occupied by thePDCCH, the N_(CCE,Mi) representing a number of CCEs in the downlinksub-frame when the value of n is Mi, and the K being an integer equal toor greater than
 1. 29. The device according to claim 25, wherein: theprocessor is configured to assign the mapping label according to anyone-to-one mapping from a set of sub-frame label i to a set of mappinglabel d.
 30. The method according to claim 29, wherein: the processor isconfigured to assign a special sub-frame at the last position.